gecko-dev/toolkit/xre/nsWindowsWMain.cpp
Henri Sivonen 3edc601325 Bug 1402247 - Use encoding_rs for XPCOM string encoding conversions. r=Nika,erahm,froydnj.
Correctness improvements:

 * UTF errors are handled safely per spec instead of dangerously truncating
   strings.

 * There are fewer converter implementations.

Performance improvements:

 * The old code did exact buffer length math, which meant doing UTF math twice
   on each input string (once for length calculation and another time for
   conversion). Exact length math is more complicated when handling errors
   properly, which the old code didn't do. The new code does UTF math on the
   string content only once (when converting) but risks allocating more than
   once. There are heuristics in place to lower the probability of
   reallocation in cases where the double math avoidance isn't enough of a
   saving to absorb an allocation and memcpy.

 * Previously, in UTF-16 <-> UTF-8 conversions, an ASCII prefix was optimized
   but a single non-ASCII code point pessimized the rest of the string. The
   new code tries to get back on the fast ASCII path.

 * UTF-16 to Latin1 conversion guarantees less about handling of out-of-range
   input to eliminate an operation from the inner loop on x86/x86_64.

 * When assigning to a pre-existing string, the new code tries to reuse the
   old buffer instead of first releasing the old buffer and then allocating a
   new one.

 * When reallocating from the new code, the memcpy covers only the data that
   is part of the logical length of the old string instead of memcpying the
   whole capacity. (For old callers old excess memcpy behavior is preserved
   due to bogus callers. See bug 1472113.)

 * UTF-8 strings in XPConnect that are in the Latin1 range are passed to
   SpiderMonkey as Latin1.

New features:

 * Conversion between UTF-8 and Latin1 is added in order to enable faster
   future interop between Rust code (or otherwise UTF-8-using code) and text
   node and SpiderMonkey code that uses Latin1.

MozReview-Commit-ID: JaJuExfILM9
2018-08-14 14:43:42 +03:00

153 lines
3.9 KiB
C++

/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef nsWindowsWMain_cpp
#define nsWindowsWMain_cpp
// This file is a .cpp file meant to be included in nsBrowserApp.cpp and other
// similar bootstrap code. It converts wide-character windows wmain into UTF-8
// narrow-character strings.
#ifndef XP_WIN
#error This file only makes sense on Windows.
#endif
#include "mozilla/Char16.h"
#include "nsUTF8Utils.h"
#include <windows.h>
#ifdef __MINGW32__
/* MingW currently does not implement a wide version of the
startup routines. Workaround is to implement something like
it ourselves. See bug 411826 */
#include <shellapi.h>
int wmain(int argc, WCHAR **argv);
int main(int argc, char **argv)
{
LPWSTR commandLine = GetCommandLineW();
int argcw = 0;
LPWSTR *argvw = CommandLineToArgvW(commandLine, &argcw);
if (!argvw)
return 127;
int result = wmain(argcw, argvw);
LocalFree(argvw);
return result;
}
#endif /* __MINGW32__ */
#define main NS_internal_main
#ifndef XRE_WANT_ENVIRON
int main(int argc, char **argv);
#else
int main(int argc, char **argv, char **envp);
#endif
static void
SanitizeEnvironmentVariables()
{
DWORD bufferSize = GetEnvironmentVariableW(L"PATH", nullptr, 0);
if (bufferSize) {
wchar_t* originalPath = new wchar_t[bufferSize];
if (bufferSize - 1 == GetEnvironmentVariableW(L"PATH", originalPath,
bufferSize)) {
bufferSize = ExpandEnvironmentStringsW(originalPath, nullptr, 0);
if (bufferSize) {
wchar_t* newPath = new wchar_t[bufferSize];
if (ExpandEnvironmentStringsW(originalPath,
newPath,
bufferSize)) {
SetEnvironmentVariableW(L"PATH", newPath);
}
delete[] newPath;
}
}
delete[] originalPath;
}
}
static char*
AllocConvertUTF16toUTF8(char16ptr_t arg)
{
// be generous... UTF16 units can expand up to 3 UTF8 units
size_t len = wcslen(arg);
// ConvertUTF16toUTF8 requires +1. Let's do that here, too, lacking
// knowledge of Windows internals.
size_t dstLen = len * 3 + 1;
char* s = new char[dstLen + 1]; // Another +1 for zero terminator
if (!s)
return nullptr;
int written =
::WideCharToMultiByte(CP_UTF8, 0, arg, len, s, dstLen, nullptr, nullptr);
s[written] = 0;
return s;
}
static void
FreeAllocStrings(int argc, char **argv)
{
while (argc) {
--argc;
delete [] argv[argc];
}
delete [] argv;
}
int wmain(int argc, WCHAR **argv)
{
SanitizeEnvironmentVariables();
SetDllDirectoryW(L"");
// Only run this code if LauncherProcessWin.h was included beforehand, thus
// signalling that the hosting process should support launcher mode.
#if defined(mozilla_LauncherProcessWin_h)
if (mozilla::RunAsLauncherProcess(argc, argv)) {
return mozilla::LauncherMain(argc, argv);
}
#endif // defined(mozilla_LauncherProcessWin_h)
char **argvConverted = new char*[argc + 1];
if (!argvConverted)
return 127;
for (int i = 0; i < argc; ++i) {
argvConverted[i] = AllocConvertUTF16toUTF8(argv[i]);
if (!argvConverted[i]) {
return 127;
}
}
argvConverted[argc] = nullptr;
// need to save argvConverted copy for later deletion.
char **deleteUs = new char*[argc+1];
if (!deleteUs) {
FreeAllocStrings(argc, argvConverted);
return 127;
}
for (int i = 0; i < argc; i++)
deleteUs[i] = argvConverted[i];
#ifndef XRE_WANT_ENVIRON
int result = main(argc, argvConverted);
#else
// Force creation of the multibyte _environ variable.
getenv("PATH");
int result = main(argc, argvConverted, _environ);
#endif
delete[] argvConverted;
FreeAllocStrings(argc, deleteUs);
return result;
}
#endif // nsWindowsWMain_cpp